1. Field of the Invention
The present invention relates to electromagnetic isolation chambers, and more particularly, relates to an electromagnetic isolation chamber with unimpeded hand entry that allows for the use of bare hands inside the chamber.
2. Description of Related Art
Electromagnetic reception and transmission is an important function of many devices, for example, cellular telephones and email devices, notebook computer wireless modems, Global Positioning System receivers, wireless data devices, and the like. Similarly, many sensitive electronic devices may be susceptible to electromagnetic signals and need to be shielded from such signals when under test. Testing, tuning, and repair of such a device can require that the Device Under Test (DUT) be isolated from, ambient electromagnetic radiation. This is sometimes necessary to permit exposing a receiving device to an unambiguous test signal free from electromagnetic interference, or to obtain a corresponding clean signal from a transmitting device. Typically, a device to be tested is placed inside an electromagnetic isolation (EMI) chamber, sometimes also known as a Faraday cage, comprising a continuous shielded enclosure which prevents ingress or egress of electromagnetic radiation. Such a chamber may take the form of an entire room, known in the art as a “screen room” for its continuous screen shielding, wherein an operator testing a device may also be enclosed in the room with the device.
A screen room can be quite expensive and therefore may not be economically feasible for a small business. Likewise, a screen room can be quite large making it unsuitable for many test or operating environments. Smaller shielded enclosures, also known as shielded boxes, capable of housing a Device Under Test but not an operator, are disclosed, for example, in U.S. Pat. No. 4,884,171 to Maserang et al.; U.S. Pat. No. 5,136,119 to Leyland; U.S. Pat. No. 5,171,936 to Suzuki et al.; and U.S. Pat. No. 5,594,200 to Ramsey. Shielded windows to permit viewing of the device under test may be provided and are disclosed, for example, in the '171 patent to Maserang et al. and the '200 patent to Ramsey. Shielded boxes are less expensive and less consumptive of space than are screen rooms; but a serious shortcoming of many shielded boxes is a lack of provision for direct tactile interaction or manipulation of the Device Under Test by an operator during testing, measuring, inspecting or tuning. Known shielded boxes require that the device to be tested be placed in the box, the box then closed, and all communication with the device be done remotely via suitably RF shielded or filtered interfaces. This prohibits, for example, an operator's making adjustments to a Device Under Test or exercising a Device Under Test directly through its normal modes of operation during testing, and may require clumsy and time-consuming workarounds to such operation which may not be entirely representative of the device in actual use. Ramsey in U.S. Pat. No. 5,594,200 discloses an enclosure with shielded gloves to permit manipulation of the Device Under Test while still maintaining shielding effectiveness. The entire disclosure of which is incorporated herein by reference. However, in use, the operator's hands are severely impeded by wearing such shielded gloves, making operation and testing of the Device Under Test clumsy, time consuming, and difficult. Additionally, such RF shielding techniques generally require the use of electrically conductive material, thus making the operator's hands, when inserted into the shielded gloves, electrically conductive and subject to electrical short circuits if they touch current carrying conductors inside the enclosure. As an example, a bare electronic printed circuit board could easily become shorted if the shielded glove were to contact the circuit traces.
It is therefore an object of the present invention to provide an improved electromagnetic isolation chamber which allows direct tactile manipulation of a device within the chamber by an operator outside the chamber using bare hands. It is a further object of the present invention to provide an improved electromagnetic isolation chamber having improved lighting and viewing of a device under test within the chamber. It is another object of the present invention to provide a conductive sleeve for upgrading an existing electromagnetic isolation chamber. It is yet another object of the present invention to provide a conductive sleeve kit for upgrading an existing electromagnetic isolation chamber.
These and other objects of the present invention are described in the detailed specification, drawings and claims contained herein.